textproduct: Albany

WHAT HAS CHANGED

Delayed onset of showers/T-storms moving into the region by 1-2 hours, with much of the activity not expected to reach western parts of the area until 10-11 pm based on latest radar trends and HRRR. Severe threat continues to look limited to the far western Mohawk Valley and possibly into the Schoharie Valley and eastern Catskills.

KEY MESSAGES

1) Scattered showers and a few non-severe thunderstorms are expected across southern areas this afternoon. Then, more numerous showers and storms are expected this evening into tonight with strong winds, large hail, and heavy rain leading to flash flooding all possible.

3) Generally tranquil weather with near to slightly below normal temperatures expected Friday into early next week.

DISCUSSION

KEY MESSAGE 1... As of 823 PM...Stable layer remains entrenched across eastern New York and western New England this evening, with a moist low level southerly flow in place. SPC Mesoanalysis shows stable conditions with any substantial CAPE displaced well to our west across central NY. Solid line of severe storms moving SE across the Finger Lakes, will continue to track SE over the next few hours then will encounter a more hostile environment in eastern NY. Still, the storms' forward momentum could still result in a few damaging wind gusts in a corridor from the W. Mohawk Valley into the Catskills based on the current trajectory. Lowered PoPs across the northern third of the area, as most of the activity should generally track along and south of I-90 later on. Even though the severe threat is fairly low, storms could still produce occasional lightning, brief gusty winds and downpours into the overnight hours.

Previous discussion from 250 PM... For this evening and tonight: GOES 16 WV imagery shows a strong cosed upper low near James Bay, with a closer upper ridge centered over Tennessee. Between these features, an upper impulse embedded in the fast flow aloft will track over the Great Lakes and Northeast this evening into tonight. Current radar already shows storms firing over southern Ontario with this feature, and these are expected to grow upscale into an MCS this afternoon/evening before tracking into our area.

A N/S oriented warm front is currently located over central NY, separating a very moist and unstable airmass from a much cooler and more stable airmass. How far east this front is able to make it this evening will determine how far east the threat for severe weather will extend. Outflow from the AM convection seems to have reinforced the cool side of the boundary/pushed it back west down towards the Catskills and Southern Tier. However, current satellite imagery shows quite a bit of clearing and instability beginning to build west of our Mohawk Valley and very close to our ADKs. If the warm front and instability are able to push closer/into the ADKs and western Mohawk Valley, this would increase the severe threat for these areas this evening. Further east, guidance is in good agreement for steepening mid-level lapse rates associated with a weak EML plume to allow for some elevated instability to work its way into our area, although SBCAPE looks to be very limited. Given expected sharp instability gradient, there remains some uncertainty in just how far east the severe threat will extend. SPC has left their D1 convective outlook across our region unchanged, with the marginal risk mainly just for our western areas. However, given current satellite and mesoanalysis trends, we can't rule out a few stronger storms as far east as the Hudson Valley or even Taconics this evening/tonight. Main threats would be damaging winds with the MCS that is expected to develop, but large hail also very much remains on the table given the presence of elevated instability, very favorable shear profiles (long straight hodographs), and elevated convection tracking on the cool side of the sfc boundary. Closer to the boundary itself in western Herkimer County, there looks to be more helicity (>200 m2s2 0-1 km layer), so an isolated tornado can't totally be ruled out although the probability is relatively low.

Other threat this evening/tonight with the MCS will be for heavy rain leading to flash flooding. There was some consideration to issuing a flood watch for the western Mohawk Valley and eastern Catskills along our border with BGM, but opted not to as the heavier rain this morning leading to more primed soils remained mainly west us. Our CWA only saw 0.1 to 0.25 inches per the NYS mesonet, and the areas that did see rain (mainly Catskills) also missed some of the heavier rain over the last couple days. Nevertheless, the environment looks favorable for heavy rain this evening and tonight with PWATs expected to 1.7 - 1.9" and warm cloud depths >12 kft. Rainfall rates of 1-2" per hour will be possible with the MCS. Main concerns would be on the southern side where more backbuilding and training is possible. Where training occurs, isolated 2-3" rainfall amounts can't be ruled out. WPC has maintained their marginal to slight risk ERO for our region, so will mention isolated to maybe scattered instances of flash flooding are possible, but just not widespread enough to justify a flood watch at this time.

Timing of this MCS has sped up slightly compared to yesterday's forecast, so it should largely be out of our area by or around 12z Thursday. The warm front may lift back north into the Mid Hudson Valley tomorrow, with up to 1000-2000 J/kg of SBCAPE expected to build south of I-90. Deep layer shear remains impressive at 35-45 kt, so on paper the environment appears favorable for a few strong storms. However, there remains a signal for fairly strong mid-level subsidence and drying in the wake of the upper shortwave tomorrow afternoon across our region. The subsidence will also help reinforce a capping inversion, and all of this may make it very hard for storms to take advantage of this favorable environment. So, severe threat is very conditional on storms being able to overcome these mitigating factors. SPC just has a general thunder risk for tomorrow for southern areas. Tomorrow will be the warmest of the next few days with highs reaching the low to mid 80s for many valley areas.

KEY MESSAGE 2...Thursday night into Friday, the front finally pushes well south of our region, thus ending the threat for severe weather through the remainder of the forecast period. An upper trough/ULL over the Golf of Maine could lead to a few isolated showers Friday or Saturday (slightly better chance as a shortwave rotates around the ULL), especially for western New England. As the upper low departs to the east Sunday into early next week and upper ridging builds back overhead, sfc high pressure builds down from the north. This should lead to mainly dry and tranquil weather through early next week. Temperatures will remain near to slightly below normal for the weekend and early next week.

AVIATION /00Z THURSDAY THROUGH MONDAY/

Through 00z Friday...Low level stratus clouds remain in place due to moist southerly flow. Cigs are at MVFR levels and should persist through much of the evening. A broken line of SHRA/TSRA are then expected to move across the area from NW to SE starting around 03z-09z. The intensity of TSRA should weaken as they move into the area, but should still produce occasional IFR conditions and downpours. After the SHRA/TSRA move through, cigs should be at IFR levels at all TAF sites through around 12z-14z, with gradual improvement to MVFR then eventually VFR during the afternoon. Winds tonight will be south-southeast around 5-15 kt, with gusts around 20 kt at KALB. Winds will shift the the west by Wednesday afternoon at 5-10 kt.

Outlook...

Thursday Night to Labor Day: No Operational Impact. NO SIG WX.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.